(19)
(11) EP 0 455 108 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
04.08.1993 Bulletin 1993/31

(43) Date of publication A2:
06.11.1991 Bulletin 1991/45

(21) Application number: 91106537.3

(22) Date of filing: 23.04.1991
(51) International Patent Classification (IPC)5: H04Q 11/00
(84) Designated Contracting States:
DE GB

(30) Priority: 27.04.1990 JP 109996/90

(71) Applicant: HITACHI, LTD.
Chiyoda-ku, Tokyo 100 (JP)

(72) Inventor:
  • Takahashi, Yasushi
    Hachioji-shi (JP)

(74) Representative: Strehl Schübel-Hopf Groening & Partner 
Maximilianstrasse 54
80538 München
80538 München (DE)


(56) References cited: : 
   
       


    (54) Coherent transmission method, crossconnect apparatus and switching apparatus


    (57) A crossconnect unit, comprising: a unit for inputting a plurality of coherent signals having a sub-signal added to a main signal (24) after said sub-signal has been modulated by one of a group of modulation methods including a frequency modulation, a phase modulation, an intensity modulation and an amplitude modulation which are different from those applied to said main signal; a wavelength filter (1) for extracting a desired signal from said plurality of coherent signals; a destination decoder (3) for detecting said sub-signal from said extracted signal and extracting destination information (22); and means (4) for setting a signal path for said extracted signal based on said destination information.






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